AT88SC0204CA-TU Atmel, AT88SC0204CA-TU Datasheet - Page 55

• Manufacturer Part Number: AT88SC0204CA-TU
• Manufacturer: Atmel

Specifications of AT88SC0204CA-TU

• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Mounting: Surface Mount
• Pin Count: 8
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Compliant

11.
11.1. Write Data to User Zones
11.2. Unlock the Configuration Memory
11.3. Write Data to the Configuration Memory
11.4. Set Security Fuses
54
Initialization Example
The first step in initializing Atmel
security settings need to be to protect this data. Once defined, determine the proper settings for CryptoMemory
registers and select values for passwords. To initialize the CryptoMemory device, the following sequence is
recommended to take place in a secure location to protect sensitive data and passwords that may be loaded into the
device.
In the default configuration from Atmel, all user zones have free access rights. Writing initial data into the user zones
should be done before setting security configurations. Use the Set User Zone command and Write User Zone
command to write initial data into the user zones. The Read User Zone command may be used to verify the data
written.
Before any data can be written to the configuration zone, it must be unlocked by presenting the correct security code
(Write 7 Password). Use the Verify Password command with the proper secure code supplied by Atmel to unlock the
configuration zone. Use the Read Config Zone command to read back the security code at address $E9 for verification
that the configuration zone has been unlocked.
Writing this data is accomplished by performing the Write Config Zone command at the appropriate address location.
The Read Config Zone command may be used to verify the data written. As soon as values are written to the registers,
keys, and passwords, they become effective in determining the security of the user zones.
Once all data is written and verified into user zones and the configuration zone the security fuses should be set before
the device is released from the secure location used for device initialization. There are three fuses, FAB, CMA and PER
that must be set. These three fuses must be set in the order listed (FAB, then CMA, then PER). The Write Fuse
command is used to set each of the three fuses individually. The Read Fuse command may be used to check the
status of all three fuses. Once all fuses have been set the Read Fuse command should return a value of zero for the
second nibble of the fuse byte.
The AT88SC0104CA is used for this example. A small pattern is written into the first two user zones. Security for each
of these two user zones and the associated register values are shown in the table below. Simple values for passwords
are used.
Table 39. Zone Configuration Example
Atmel AT88SC0104/0204/0404/0808/CA
User Zone
0
1
2
3
Zone 0 Data
Zone 1 Data
Zone 2 Data
Zone 3 Data
Data
®
None
Read/Write Password (Set 1)
Read/Write Authentication (Set 2)
Read/Write Password (Set 1),
Read/Write Authentication (Set 1)
with Encryption Required
CryptoMemory
Security Requirements
®
is to determine what data is to be stored in the device and what the
Access Register
$DF
$FF
$7F
$57
Password/Key
Register
8664C–CRYPT–01/10
$BF
$FF
$F9
$B9